The instant invention relates to an altered flower phenotype in plants belonging to the genera Osteospermum and Dimorphoteca, which is induced by a mutant allele, as well as to the method of breeding Osteospermum and Dimorphoteca plants having this altered flower phenotype. All publications cited are hereby incorporated by reference.
The genus Osteospermum was introduced as a commercial bedding plant in the beginning of the nineties of the last century. Since then this genus has been very successful in the horticultural market. For 2008, worldwide sales were estimated at almost 100 million plants.
The genus Osteospermum is a South African native and belongs to the plant family of the Asteraceae. It comprises almost 70 different species representing a broad range of either evergreen shrubs or herbaceous plants with growing habits varying from erect to prostrate. The existing Osteospermum cultivars are thought to be interspecific hybrids of the following main species: O. ecklonis, O. barbariae, O. caulescens, O fruticosum, O. jucundum, and O. chrysanthemifolia. The first breeding with Osteospermum was started between 1970 and 1985 by British hobby breeders and later continued mainly by Danish and Japanese breeders (Allavena, A., et al., Genetic engineering of Osteospermum ssp.: a case story, Acta Hort., 508, 129-133 (2000)). According to Faccioli, et al., professional breeders used the British plant material as well as accessions from South Africa to breed new hybrids (Faccioli, P., et al., Genetic diversity in cultivated Osteospermum as revealed by random amplified polymorphic DNA analysis, Plant Breed., 119, 351-355 (2000)). During further breeding, which was mainly done by professional Danish and German breeding companies, crossings between the existing varieties were made to improve the quality. This approach has resulted in a narrow gene pool of the plant material, which is commercially available today. For commercial production, Osteospermum and Dimorphoteca plants are mostly propagated asexually by cuttings. However, sexual propagation through seeds is also possible and several seed propagated varieties are on the market.
The genera Osteospermum and Dimorphoteca are very closely related and, in some cases even the distinction of both genera or the classification of certain varieties into these two genera is unclear. In the past the genus Osteospermum belonged to the genus Dimorphoteca, but today Dimorphoteca only comprises the annual species, whereas all semi-perennial species fall into the genus Osteospermum. Crossbreeding between both genera is possible and several commercial varieties result from interspecific hybridisation between an Osteospermum and a Dimorphoteca parent. The different Osteospermum and Dimorphoteca cultivars, breeding lines and wild species represent a broad range of different ploidy levels varying from 2× up to almost 8×, which also shows that during the development of today's cultivars hybridisation between species took place.
Commercially available Osteospermum plants flower from early spring to autumn. The typical flower is a capitulum (flower head) with tubular central disc florets surrounded by a ring of ray florets, which gives the flowers the typical daisy shape (Faccioli, P., et al., Genetic diversity in cultivated Osteospermum as revealed by random amplified polymorphic DNA analysis, Plant Breed., 119: 351-355 (2000)). Colour and shape of ray florets as well as the colour of the disc florets vary. The colour of the upper surface of the ray florets, which in colloquial language are called petals, is determined by two independent metabolic pathways producing carotenoids, visible as yellow-orange-brown colours, and anthocyanins, resulting in white to pink and purple flower colours (Seitz, C., Klonierung and Charakterisierung von Flavonoidgenen aus Osteospermum, Dissertation an der Technischen Universität München (2004)). Intensive breeding work during the past several years has resulted in a broad range of white, pink, purple, yellow, and orange petal colours and new mixes of the carotenoid and anthocyanin colour groups, as well as in colour patterns like eye types or stripes. Similar to the colour range of the upper surface, the colour of the lower surface of the ray florets also varies from light to dark colours in the bluish-pink or yellow-brown colour range. The colour pattern usually is striped with the coloured stripes running parallel to the petal edges. Typically, the colour of the disc florets is darker than the colour of the ray florets and it may vary from grey to blue, violet or purple or from dark yellow to dark brown. The usual shape of the ray floret is obovate, but in some genotypes the petal edges are rolled upwards resulting in so-called spoon or spider types.
The foregoing examples of the related art and limitations related therewith are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent to those of skill in the art upon a reading of the specification.